Conventionally, for such an electronic component, which for instance may consist of a super high speed electromagnetic delay line, a ground electrode is formed on the reverse surface of a rectangular dielectric base plate, and an electroconductive line folded back and forth along the widthwise direction of the base plate as it extends along its longitudinal direction is formed on the front surface of the dielectric base plate. Terminal pieces connected to the ground electrode and the electroconductive line project from an end of the dielectric base plate.
According to such an electromagnetic delay line, since the electroconductive line serving as a delay line device forms a super high speed impedance line of approximately 50 ohms, it can be connected to an impedance circuit of a printed circuit board in a favorable matching condition only when an appropriate impedance line typically constructed as a micro strip of 50 ohms is formed in this printed circuit board.
However, according to such an electromagnetic delay line equipped with terminal pieces, the terminal pieces have a certain inductive component and often do not form an impedance line of 50 ohms. Conventionally, the impedance of terminal pieces has been disregarded. Therefore, it often happened in the past that the frequency property was impaired by the mismatch at the terminal pieces even when the frequency property of the electroconductive line was quite favorable, and that the electroconductive line was thereby rendered unable to produce a desired super high speed property.
It is conceivable to make a part of the ground electrode oppose the signal terminal piece with a dielectric body placed therebetween and form a distributed capacitance between the signal terminal piece and the ground electrode so as to utilize the signal terminal piece as an appropriate impedance line similar to a micro strip line and to prevent a mismatch at the signal terminal piece. However, according to such a structure, it is necessary to form a dielectric body and a ground terminal in a certain fixed relationship with the signal terminal piece, and its fabrication process is inevitably made substantially more complex.